Hydrogenation of hydrocarbons



,Dec. 2-2, 1936. A. szAYNA K 2,065,201

YDROGEATION OF HYDROCARBONS 4 Filed June 6, 1931 ATTORNEYS` Patented Dec. 22, 1936 UNE'ED STATES HYDROGENATION F HYDROCARBNS Antoni Szayna, Lwow, Poland, assigner to Sinclair Reining Company, New York, N. Y., a

corporation of Maine Application June 6, 1

2 Claims.

It isradvantageous in many instances, in the processing of petroleum stocks, to have stock relatively free from asphaltic matter. Asphaltic matter, or potential coke as it is sometimes designated, tends to form carbonaceous aggregates, `presumably by polymerization, at elevated temperatures, and these carbonaceous aggregates, solid or semi-solid in character, tend to precipitate and deposit in processing apparatus. Such precipitation and deposit of these carbonaceous aggregates involve numerous diiilculties and disadvantages. Stocks free from such asphaltic matter have come to be known as clean stocks, as distinguished from dirty stocks containing such asphaltic matter in substantial amounts.

This invention relates to an improved method of freeing petroleum stocks, particularly residual stocks, from asphaltic matter, or, in other words, to the production of clean stocks from dirty stocks.

I have discovered that hydrogenation of petroleum stocks containing asphaltic matter, under appropriate conditions, produces a change n in the stock or stock mixture the result of which is to alter asphaltic matter present in the original stock, even though present as an apparently stable dispersion, to a form such that it can be quickly precipitated or coagulated and easily separated from the stock or stock mixture. In some respects the precipitation resembles the action of precipitants such as sulphuric acid and iron and calcium chlorides, but I do not at present have any complete explanation of the phenomenon. The conditions appropriate to the result involve the formation of some low boiling oil, by cracking of the stock or part of it, and the presence of these formed low boiling oils may cooperate to produce the result. However, the invention is not predicated upon any particular hypothesis. According to my invention, the petroleum stock containing asphaltic matter is heated to a temperature upwards of 800 F. in the presence of hydrogen in amount upwards of 0.5% by weight on the stock for a period of time longer or shorter asthe temperature is lower or higher, the resulting stock mixture is thereafter cooled to a temperature not exceeding about 200 F. and the precipitated asphaltic matter is then mechanically separated from the cooled stock mixture.

In referring to mechanical separation I refer to operations such as settling and decantation, under atmospheric pressure or under higher pressure, as distinguished from thermal separation by operations such as distillation or chemical separation by operations such as acid treatment. At a temperature of 800 the period of high temperature treatment may approximate, for example, 10-12 hours, at S30-880 F. it may approximate, for example, minutes and at 930- 931, Serial No. 542,579

(Cl. 19H-53) 950 F. it may approximate, for example, 10 minutes. Hydrogen concentrations in the range of 0.54.0% by weight on the stock are in general useful in carrying out the invention; higher concentrations are operative but usually are uneconomical. An initial separation of precipitated asphaltic matter may be eiiected, particularly when the stock is heated in the presence of hydrogen in the higher range of temperatures, for example, S900-950 F., while the stock mixture is still hot. When the stock mixture is heated in the presence of hydrogen in a higher range of temperatures some coke may be formed which with associated altered asphaltic matter may with advantage be separated from the stock mixture before the latter is cooled. By limiting the temperature to which the stock is heated in the presence of hydrogen, the formation of such coke may be avoided and the precipitation and separation may be effected entirely after the stock mixture is cooled.

Fig. l of the accompanying drawing illustrates, diagrammatically, the operation of the improved method of the invention.

Fig. 2 illustrates one conventional form of apparatus for effecting separations by settling and decantation.

Referring to Fig. 1 of the drawing, the hydrogenation is carried out at l, an optional hot separation of precipitated asphaltic matter and any coke is carried out at 2 and the cold separation of precipitated asphaltic matter and associated oil is carried out at 3. The hydrogenation may be carried out in a closed reaction chamber or in a tubular heater or in a tubular heater discharging into a closed reaction chamber. The hot separation may be carried out in a closed chamber, a part of a reaction chamber in which the hydrogenation is carried out or a separate chamber. The cold separation may be carried out in a receiving chamber connected to the hydrogenation apparatus or the hot separation apparatus through a condenser or cooler maintained under the reaction pressure or under a lower pressure. The stock separated from asphaltic matter in the cold separation operation is discharged to fractionation apparatus or other apparatus appropriate to the further treatment to which the stock is to be subjected.

In the apparatus illustrated in Fig. 2 of the drawing, the mixture from the hydrogenation operation enters the chamber 2 and there is subjected to settling and then to decantation. The heavier liquid phase, including any suspended coke particles, is drawn oi from the lower portion of the chamber 2 through one or more of the several valved connections communicating with the lower portion of chamber 2. The lighter liquid phase is discharged from the upper portion of the chamber 2 through one or more of the several valved connections communicating with the upper portion of the chamber 2. The lower end of the chamber 2 advantageously is flanged to permit the removal of any coke that may settle and accumulate in the lower portion hydrogenation operation is required to pass before entering the chamber 2. If the separation and decantation which take place in the chamber 2 are effected at a high temperature, the lighter liquid phase discharged from the upper portion of the chamber 2 may be passed through a Suitable cooler to a second separating chamber 3. The temperature in the chamber 3 may be controlled by circulating a cooling medium through the cooler through which the stock, partially freed from asphaltic matter, flows in passing from the chamber 2 to the chamber 3. Withdrawal of the settled heavier liquid phase from the lower portion of the settling chamber 3 and of the lighter liquid phase from the upper portion of the chamber 3, through suitable valved connections, may be eifected in a manner similar to that described in connection with the operation of the settling chamber Z. If it is desired to eifect the separations of the liquid phases l which occur in either of the chambers 2 or 3 at a pressure lower than that prevailing in the hydrogenation operation, the desired pressure reduction may be assisted by venting gases from the upper end of the separating chamber. If it is not desired to effect an intermediate hot separation, the temperature of the mixture leaving the hydrogenation operation may be reduced to less than 200 F. before entering the chamber 2 by suitable control of the flow of cooling medium through the preliminary cooler. A cold separation may thus be effected in the chamber 2. The subsequent cooler and the separating chamber 3 are not required when the apparatus is operated in this manner.

Following the hydrogenation and the subsequent cooling, the stock mixture separates, almost immediately, into two distinct and apparently immiscible liquid phases the lighter of which is substantially free from asphaltic matter and the heavier of which, sometimes as little as 2% but frequently about of the total, contains the precipitated asphaltic matter. The heavier liquid phase may also include some coke at ordinary temperature.

For example: A Mid-Continent reduced crude oil of 24.0 A. P. I. gravity was heated to a temperature of about 880 F. in the presence of hydrogen in amount approximating 3.1% by weight on the stock for a period of sixty minutes under a maximum pressure of 267 atmospheres. After cooling to ordinary temperature the hydrogenated stock mixture separated immediately into a lighter phase and an immiscible heavier phase, the latter approximating somewhat less than 20% of the total. After separation the lighter phase was fractionated to recover about 53% by Weight on the original stock of 391 F. end point gasoline and 27% of clean higher boiling oil. The heavier phase contained about 2% yof precipitated asphaltic matter. No coke was formed.

'Ihe invention is of general application in the separation of asphaltic matter from petroleum stocks containing such matter, in large or in small amounts. The invention is applicable, as illustrated in the example just given, to the production of clean higher boiling oil such as gas oil from dirty crude stocks with the concurrent production of gasoline. The gasoline production need not be as large or it may be larger than that recovered in the particular operation of the foregoing example. The invention is also applicable to the production of bright stocks from residual crude stocks containing asphaltic matter. This application of the invention would include the stripping of the formed low boiling oil from the high boiling viscous bright stock. The invention is also .applicable to the production of clean gas oil, for example, from dirty residual stocks such as tar discharged as a residue from pressure stills operated to produce lower boiling oils from higher boiling oils by cracking.

The hydrogenation may be carried out, for example, under pressures in the range of 100-300 atmospheres. Catalysts are not required. In one'aspect this is an important advantage of this invention since, mechanically, suspended solid catalysts involve most of the same dii'culties and disadvantages involved by suspended coke.

I claim:

l. In the separation of asphaltic matter from petroleum stock containing such matter, the improvement which comprises heating the stock to a temperature upwards of 800 F. and under a pressure upwards of 100 atmospheres in the presence or" hydrogen in amount upwards of 0.5% by weight on the stock, whereby hydrogenation and some cracking occur, cooling the resulting stock mixture to a temperature not exceeding about 200 separating the cooled stock mixture by gravity into a relatively light liquid phase substantially free from asphaltic matter and a re1- atively heavy liquid phase containing precipitated asphaltic matter, and separately discharging from the Zone of separation the relatively light liquid phase substantially free from asphaltic matter.

2. In the separation of asphaltic matter from petroleum stocks containing such matter, the improvement which comprises heating the stock to a temperature upwards of 800 F. and under a pressure upwards of 100 atmospheres in the presence of hydrogen in amount upwards of 0.5% by weight on the stock, whereby hydrogenation and some cracking occur, effecting by gravity an initial separation of the stock mixture while the latter is still hot into a relatively light liquid phase and a relatively heavy liquid phase containing precipitated .asphaltic matter, separately discharging the relatively light liquid phase from the zone of initial separation and cooling the said relatively light liquid phase to a temperature not exceeding about 200 F., separating by gravity the material thus cooled into a lighter liquid phase substantially free from asphaltic matter and a heavy liquid phase containing precipitated asphaltic matter, and separately discharging from the second Zone of separation the lighter liquid phase substantially free from asphaltic matter.

ANTONI SZAYNA. 

